Dear Osmocom community, About a year ago I published this specification:
https://www.freecalypso.org/specs/tw-ts-001-v010001.txt TW-TS-001 is a spec, written in 3GPP language style, for enhanced RTP transport of FR and EFR codec frames in an IP-based GSM RAN. I got OsmoBTS support for this RTP extension on branch falconia/rtp_traulike, but I never submitted it to Gerrit for mainlining: when I mentioned it in OsmoDevCall in 2023-06, the feedback from Harald was that the extension would need to be somehow requested from the CN via signaling, rather than manually switched on via OsmoBTS local vty. Since then I have familiarized myself with 3GPP specs for AoIP user place (TS 48.103 and TS 26.102 it refers to), and I see the problem with my initial "brute force" method: when 3GPP specs explicitly call for standard RTP formats at the AoIP interface, intentional deviations from that standard need to be negotiated/signaled in some clean manner. So here is my new solution: https://www.freecalypso.org/specs/tw-ts-001-v010100.txt https://www.freecalypso.org/specs/tw-ts-002-v010100.txt https://www.freecalypso.org/specs/tw-ts-003-v010001.txt There are 3 new specs in the above set: * The new version of TW-TS-001 clarifies some deficiencies in the original, and refers to TW-TS-003 for how the enhanced RTP format is to be invoked at the AoIP interface. * TW-TS-002 is a new spec that does for HRv1 codec what TW-TS-001 does for FRv1 and EFR. The enhanced RTP payload format here is an extension of RFC 5993, which I named super-5993. * TW-TS-003 is an extension to BSSMAP for communicating the use of enhanced RTP payload formats between MSC and BSS. I will now be preparing some patches for TW-TS-003 support - see you in Gerrit code review soon. :-) With love and greetings from Themyscira, Mother Mychaela
